The present invention relates generally to aviation electronics (avionics) systems. More particularly, the present invention relates to a modular communications, navigation and identification (CNI) system having an architecture which allows modules and/or communication pathways to be reconfigured in the event of a partial system failure.
CNI avionics systems integrate a number of functional modules (also known as assets) for use in performing various essential functions. Integrated sensor subsystems which transmit and receive data in various tailored formats for specific functions typically include sensor modules such as a receiver/exciter, an antenna and an antenna interface. Each of these integrated sensor subsystems is used to perform a different function such as VHF radio communications, UHF radio communications, data link communications for processing information about a nearby airport which is needed for use by the avionics systems, transponder functions and integrated landing system (ILS) functions. These integrated sensor subsystems communicate, through cryptographic processors, with other modules, computer systems and/or human interfaces. Typically, for security reasons, it is preferred to maintain data used by the CNI system computers or human machine interfaces (sometimes referred to as red data) separate from data used by the integrated sensor subsystems (sometimes referred to as black data). For this reason, the cryptographic processors encode and decode information communicated between the integrated sensor subsystems and the other modules or subsystems of the CNI avionics system.
Typically, a communication link between a particular integrated sensor subsystem and a computer system or human interface module is hard wired through a particular cryptographic processor to define a communications path (also known as a thread). Thus, if the communication path between a particular integrated sensor subsystem and another module stops functioning properly, for instance due to the malfunction of the associated cryptographic processor, the functions performed by the particular integrated sensor subsystem cannot be performed until maintenance on the CNI avionics system is available. This is an undesirable result because of the fact that higher priority integrated sensor subsystem functions may be lost while lower priority integrated sensor subsystem functions are still available.